Fluidised bed device

ABSTRACT

Fluidised bed device for draining and/or cooling fine granular products, having a perforated bed and a chest for supplying air into said bed; the assembly of said bed and said chest supported by springs on a stationary frame; a vibrator causing vibration of said assembly; one of said springs being a helical spring arranged perpendicular to the centre of gravity of said assembly and bearing the weight of said assembly; the other of said springs being plate springs arranged remote from said helical spring and guiding said assembly relatively to said frame.

United States Patent 11 1 Biagg'i @ct. 30, 1973 [5 FLUIDISED BED DEVICE 3,003,667 10/1961 .lonsson 1 1 34/164 5] Inventor: J q gg vine y, 3,022,988 2/1962 Corson et a1. 34/164 France [73] Assignee: Escher Wyss Aktiengesellschaft, Exam" 'e' Kenneth Sprague Zurich, Switzerland ASSlSldfll Exammer-James C. Yeung AttorneyAustin P. Dodge et al. [22] Flledz Apr. 19, 1972 Appl. No.: 245,466

[30] Foreign Application Priority Data Apr. 19, 1971 France 7113669 [52] 11.8. C1... 34/164, 198/220 R [51] Int. Cl. F26b 9/00 [58] Field of Search 34/164, 57 R; 198/218, 220 DD, 220 R [56] References Cited UNITED STATES PATENTS 3,161,483 12/1964 Morris 34/164 2,985,279 5/1961 Burgess, Jr. 198/220 DD 2,094,786 10/1937 Flint 34/164 ABSTRAQT Fluidised bed device for draing and/or cooling fine granular products, having a perforated bed and a chest for supplying air into said bed; the assembly of said bed and said chest supported by springs on a stationary frame; a vibrator causing vibration of said assembly; one of said springs being a helical spring arranged perpendicular to the centre of gravity of said assembly and bearing the weight of said assembly; the other of said springs being plate springs arranged remote from said helical spring and guiding said assembly relatively to said frame.

4 Claims, 1 Drawing Figure FLUIDISED BED DEVICE BACKGROUND OF THE INVENTION The invention relates to fluidised bed devices used for drying and/or cooling fine granular products, for example powders, grains or crystals. Said fluidised bed devices comprise a bed of elongated form, traversed throughout its lenght by the product which is to be dried and/or cooled. Beneath the perforated bottom of the bed there is provided an air supply chest. Furthermore, the assembly formed by the bed and the air supply chest is subjected to unidirectional vibrations, which are transmittedto it by one or more vibrators.

For this purpose, in known fluidised bed devices, the vibrated assembly is connected to a stationary frame by means of a series of inclined plate springs distributed throughout its length. These plate springs thus serve a double purpose, since firstly they support the weight of the vibrated assembly and secondly they ensure the guiding of the assembly while it is vibrating. This solution presents some disadvantages, just because these plate springs have to serve a double function. In effect, under the action of the weight of the supported assembly, the plate springs become deformed. Under this condition, they provide an imperfect guiding of the vibrated assembly when the latter is not perfectly balanced.

In another known device, helical springs are provided as support or suspension between the vibrating assembly and the stationary frame. However, the assembly is not satisfactorily guided by these springs, since the springs change their length with an alteration in the weight of the chamber and under the influence of the vibratory forces.

Furthermore, with known devices, the vibrators are arranged at the end of the bed. Consequently, strong forces are necessary for guiding the assembly relatively to the stationary frame. Furthermore, the assembly has to be reinforced in the region where the vibrators are fixed to it.

one or more plate springs, or other springs being elastic in the direction of vibration but fast in the direction perpendicularto the direction of vibration, which plate springs or springs are'disposed on the assembly for connecting it tothe stationary frame, so as to ensure the stability of the vibrated assembly and the guiding thereof while it is vibrating.

Hence, the two functions formerly allotted alone to the plate springs, or alone to the helical springs, each of them provided throughout the length of the known devices are now separated, the weight of the vibrated assembly being supported by helical springs while the guiding of the assembly is assured by the plate springs.

However, according to another important feature of the present device, the vibrator or vibrators adapted to excite the vibrated assembly are carried by the stationary frame, and these vibrators act on the said assembly by means of thrust rods or tubes which only transmit the effective component of the vibration and of which the ends are attached to the assembly close to its centre of gravity.

BRIEF DESCRIPTION OF THE DRAWING However, other features and advantages of the invention will become apparent from the following description of one embodiment thereof. This description is given by reference to the accompanying drawing given simply by way of indication and in which the single FIGURE is a diagrammatic side elevation of a fluidised bed device.

DESCRIPTION OF THE PREFERRED EMBODIMENT The shown fluidised bed device comprises a bed I designed to be traversed throughout its length by the product which is to be dried and/or cooled. At its one end, this bed 1 is provided with a funnel 2 for the introduction of the product, while it has at its other end an orifice 3 for the outlet of the product after it has been dried and/or cooled.

The bottom-of the bed 1 is formed by a horizontal sheet metal bottom plate 4 having a large number of fine perforations. Provided beneath the bottom plate 4 is a chest 5 of the general form of a rectangular parallelepiped, which extends throughout the length of the bed 1. The purpose of the chest 5 is to supply the bed with air which passes through the perforations in the bottom plate 4 and dries and/or cools the product. The air also ensures fluidisation of the product which is disposed above the bottom plate 4 and which travels from the funnel 2 to the outlet orifice 3.

At its one end, the chest 5 carries a union 6 connected to an air supply pipe 7. The other end of the chest 5 is completely closed off, so that the air escapes into. the interior ofthe bed 1. This latter comprises a hood for the evacuation of the air and,.for this purpose, it has at its upper end two outlet chimneys 8. The assembly formed by the bed 1 and the chest 5 is adapted to be excited with vibratory movements.

According to the invention, this assembly 1, 5 rests perpendicularly of its centre of gravity G on helical springs 9. These springs 9, one of which is seen, are arranged one behind the other in a direction perpendicular to the drawing, and are supported on blocks 10 integral with a stationary frame 11 of the device.

The helical springs 9 may possibly be replaced by rubber blocks or other members capable of elastically supporting the weight of the vibrated assembly 1, 5, while. permitting the latter to perform the vibratory movements.

At both its ends, the assembly 1, 5 is connected to the stationary frame 11 by groups of plate springs 12a or 12b respectively. At their ends, these plate springs are respectively embedded in a support fixed to the frame 11 and in another support fixed to the vibrated assembly. The only purpose of these two groups of plate springs 12a and 12b is to ensure the stability of the vibrated assembly 1, 5 and also the guiding thereof. However, they are not called upon to bear the weight of the assembly 1, 5, because this function is allotted to the helical springs 9 provided perpendicularly of the centre of gravity G.

The vibrating of the assembly 1, is assured by vibrators 13 comprising unbalanced shafts turning in opposite directions so as to provide unidirectional vibrations. However, these vibrators 13 are not fixed on the vibrated assembly 1, 5. They are supported by the stationary frame 11, their casing bearing on this frame 11 by means of helical springs 14 or any other suitable resilient members. Thereby the vibrators 13 are arranged at the one end of the frame 11.

According to another novel feature of this device, the transmission of the vibration forces is assured by a number of thrust tubular rods 15, of which the ends are attached to the vibrated assembly 1, 5 in the region of the centre of gravity G of the latter. One of the rods 15 is seen, the other ones lie behind it, arranged in a plane perpendicular to the drawing.

The rods are slender, that is their axes are easily bent, and they are inclined and extend through the chest 5 by means of passages formed in the latter, the sealing action for each rod being assured by means of a stuffing box of conventional type.

As the vibrating forces are introduced into the assembly l, 5 in the region of the centre of gravity G, reinforcement of the assembly is no longer necessary. Furthermore, as the vibrators l3 lie on the stationary frame 11, simple variation of speed of the vibrators during operation is achieved. It is thus possible to change the frequency of the vibrations.

In any case, the speed of advance of the product can be modified during operation so as to adapt the device at any moment to the rate of flow or the quality of the product which it is receiving.

Furthermore, it is obvious that the present device is not limited to the single embodiment which has been described above simply by way of indication, and to which various modifications can be made.

I claim:

1. A fluidised bed device for drying and/or cooling fine granular products comprising a. a stationary frame;

b. an assembly including a bed for transporting said products which is provided with a perforated bottom, and an air chest located below said bottom;

0. a vibrator for subjecting the assembly to undirectional vibration;

d. first spring means located in a vertical plane containing the center of gravity of the assembly and serving to support the assembly on the frame, the spring means being elastic in the vertical direction and being yieldable in the direction of vibration; and

e. second spring means spaced from the first spring means in the direction of vibration and reacting between the frame and the assembly to guide the latter during vibratory motion, the second spring means being elastic in the direction of vibration and rigid in a direction normal thereto.

2. A fluidised bed device as defined in claim 1 in which the second spring means is defined by two sets of springs located, respectively, at opposite sides of the first spring means in the direction of vibration.

3. A fluidised bed device as defined in claim 1 in which the vibrator is coupled to the assembly by forceimparting means connected to the assembly in the region of its center of gravity.

4. A fluidised bed device as defined in claim 3 in which a. the vibrator comprises at least one vibrationgenerating unit mounted on the frame; and

b. the force-imparting means comprises a thrust rod connected at one end to the assembly in the region of its center of gravity and coupled at its opposite end to said generating unit. 

1. A fluidised bed device for drying and/or cooling fine granular products comprising a. a stationary frame; b. an assembly including a bed for transporting said products which is provided with a perforated bottom, and an air chest located below said bottom; c. a vibrator for subjecting the assembly to undirectional vibration; d. first spring means located in a vertical plane containing the center of gravity of the assembly and serving to support the assembly on the frame, the spring means being elastic in the vertical direction and being yieldable in the direction of vibration; and e. second spring means spaced from the first spring means in the direction of vibration and reacting between the frame and the assembly to guide the latter during vibratory motion, the second spring means being elastic in the direction of vibration and rigid in a direction normal thereto.
 2. A fluidised bed device as defined in claim 1 in which the second spring means is defined by two sets of springs located, respectively, at opposite sides of the first spring means in the direction of vibration.
 3. A fluidised bed device as defined in claim 1 in which the vibrator is coupled to the assembly by force-imparting means connected to the assembly in the region of its center of gravity.
 4. A fluidised bed device as defined in claim 3 in which a. the vibrator comprises at least one vibration-generating unit mounted on the frame; and b. the force-imparting means comprises a thrust rod connected at one end to the assembly in the region of its center of gravity and coupled at its opposite end to said generating unit. 